The objective of these studies is to elucidate structure and functional relationships in biological membranes by investigating the effects of bacteriophage and other extra-chromosomal genetic elements (plasmids) on the cell surface of Escherischia coli. Specific aims include the elucidation of the mechanism of killing of bacteria by T-even bacteriophage ghosts; characterization of membrane proteins induced by T4, T5, and lambda bacteriophage as to mode of synthesis, topographical location in the membrane, and function; investigation of the factors which affect the insertion of these proteins into membrane both in vivo and in vitro; investigation of membrane protein biosynthesis by T3 and T7 phage and F and RTF plasmids; investigation of the possibility that the many cases of exclusion of virulent phage by plasmids or lysogenized phage all occur by a common mechanism and formulation of a theory that would explain this exclusion and other cell surface changes caused by viruses and other extra-chromosomal genetic elements. Methodology includes the comparison of membrane proteins induced by wild type and mutant phage or plasmids with host membrane proteins using analytical gel-electrophoresis and sucrose gradient centrifugation, and the study of permeability changes induced by certain combinations of genetic information within the cell.